U.S. patent number 8,244,419 [Application Number 11/923,254] was granted by the patent office on 2012-08-14 for marine power train system and method of storing energy in a marine vehicle.
This patent grant is currently assigned to Mi-Jack Canada, Inc.. Invention is credited to John David Watson, Frank Wegner-Donnelly.
United States Patent |
8,244,419 |
Wegner-Donnelly , et
al. |
August 14, 2012 |
Marine power train system and method of storing energy in a marine
vehicle
Abstract
A marine power system comprises a motor for providing
propulsion. It also comprises an energy storage unit (ESU) for
storing and supplying energy to the motor. A prime power system is
connected to the ESU and motor for selectively providing energy to
these subsystems through a bus. The motor selectively receives
energy from the prime power system and the ESU and can supply
regenerative braking energy to the bus. The system can also
accommodate multiple generator sets providing system power. The ESU
can also provide starting power for the prime power system.
Alternately, the prime power system drives a mechanical power
system output shaft connected to the motor, and the marine system
comprises an alternator driven by the prime power system output
shaft. The ESU can transmit energy to the alternator. The prime
power system can be located on a tugboat displacing a barge
carrying the energy storage unit.
Inventors: |
Wegner-Donnelly; Frank (North
Vancouver, CA), Watson; John David (Evergreen,
CO) |
Assignee: |
Mi-Jack Canada, Inc. (Hazel
Crest, IL)
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Family
ID: |
39668505 |
Appl.
No.: |
11/923,254 |
Filed: |
October 24, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080182466 A1 |
Jul 31, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60862728 |
Oct 24, 2006 |
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Current U.S.
Class: |
701/21; 307/10.1;
307/80; 318/376; 307/9.1; 440/1; 440/6; 440/84; 290/40C; 440/87;
440/50; 105/61; 440/85; 307/43; 307/85; 318/154; 318/139; 307/71;
440/3; 290/3; 701/36; 290/31 |
Current CPC
Class: |
B63H
23/24 (20130101); B63J 3/02 (20130101); B63J
3/04 (20130101); Y02T 90/40 (20130101) |
Current International
Class: |
B60L
3/00 (20060101); H02P 3/14 (20060101); B60W
10/04 (20060101); H02J 1/00 (20060101); F02D
29/06 (20060101); G06F 7/00 (20060101); B61C
3/00 (20060101) |
Field of
Search: |
;701/21 ;440/84 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2431354 |
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Jun 2002 |
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CA |
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WO97/40999 |
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Nov 1997 |
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WO |
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WO 2005007444 |
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Jan 2005 |
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WO |
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WO 2006020587 |
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Feb 2006 |
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WO |
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WO 2006020667 |
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Feb 2006 |
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WO |
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WO2007/068514 |
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Jun 2007 |
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WO |
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Other References
US. Appl. No. 60/745,153, filed Apr. 19, 2006, Donnelly et al.
cited by other .
U.S. Appl. No. 60/814,595, filed Jun. 15, 2006, Donnelly. cited by
other.
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Primary Examiner: Trammell; James P
Assistant Examiner: Alsomiri; Majdi
Attorney, Agent or Firm: McCracken & Frank LLC
Parent Case Text
The present application claims priority of U.S. Provisional patent
application No. 60/862,728 filed Oct. 24, 2006, the contents of
which are incorporated herein by reference.
Claims
The invention claimed is:
1. A marine power system comprising: i) at least one motor for
driving a propulsion unit having a propulsion unit average power
and a propulsion unit peak power; ii) at least one energy storage
unit for storing electric energy and supplying said electric energy
to the at least one motor, having an energy storage capacity and an
energy storage unit output power; iii) at least one prime power
system having a prime power system rated power, being electrically
connected to the at least one energy storage unit and the at least
one motor for selectively providing electrical energy to the at
least one energy storage unit and to the at least one motor; iv) a
bus electrically connecting the at least one energy storage unit,
the at least one prime power system and the at least one motor; and
v) a control system for controlling the operation of the at least
one prime power system and the propulsion unit, and for monitoring
the at least one energy storage unit, wherein the at least one
motor selectively receives operational energy from the at least one
energy storage unit and the at least one prime power system, the at
least one motor supplies regenerative braking energy to the bus
when the propulsion unit collects energy from water passing by the
propulsion unit, and wherein the ratio of the at least one prime
power system rated power to the propulsion unit peak power is
between 0.1 and 0.8.
2. The marine power system of claim 1, further comprising an
alternator driven by the at least one prime power system, the
alternator being electrically connected to the bus, wherein the at
least one energy storage system provides starting power for the at
least one prime power system.
3. The marine power system of claim 1, further comprising: a
plurality of electrical energy converters operable to convert
energy to electrical energy having a desired electrical
characteristic, the plurality of electrical energy converters
comprising first and second electrical energy converters having
respectively first and second output voltages and first and second
output currents, the plurality of electrical energy converters
being electrically connected to the bus, wherein a plurality of
prime power systems provide energy to the plurality of electrical
energy converters, the plurality of prime power systems comprising
first and second engines corresponding respectively to the first
and second electrical energy converters; the bus being operable to
transport electrical energy from the electrical energy converters
to the at least one motor, and wherein, at a selected time, the
relationship between at least one of a current level and a voltage
level of the bus on the one hand and at least one of the first and
second output currents and the first and second output voltages of
the first and second electrical energy converters on the other hand
determines, at the selected time, which of the first and second
engines supplies energy to the bus through the corresponding
electrical energy converter.
4. The marine power system of claim 1 wherein the at least one
prime power system comprises a prime power source selected from the
group consisting of engines, diesel engines, gas turbine engines,
microturbines, Stirling engines, spark ignition engines, fuel
cells, solar cells, grid power, power induction systems, wind
turbines and a combination thereof.
5. The marine power system of claim 1 wherein the energy storage
unit comprises an energy storage system selected from the group
consisting of a battery pack, a bank of capacitors, a compressed
air storage system, a hydraulic accumulator, one or more flywheels
and a combination thereof.
6. The marine power system of claim 1 wherein the energy storage
unit forms part of a ballast in a marine vehicle.
7. The marine power system of claim 1 further comprising a
power-dissipating load for dissipating excess regenerative braking
energy on the electrical bus, wherein the power-dissipating load is
mounted on a marine vehicle under water.
8. The marine power system of claim 1 further comprising an
auxiliary power system connected to the electrical bus.
9. The marine power system of claim 1 wherein the control system
comprises a controller selected from the group consisting of analog
devices, programmable logic controllers and computers.
10. The marine power system of claim 1, wherein the at least one
energy storage unit and the at least one prime power system are
sized and provided in a form adapted to retrofit with an existing
receiving means on a marine vehicle for receiving a diesel engine
and a generator set.
11. The marine power system of claim 1 wherein the at least one
energy storage unit provides power regulation to the at least one
prime power system.
12. The marine power system of claim 1, wherein the propulsion unit
comprises a drive system selected from the group consisting of
screws, propellers, and jet pumps.
13. The marine power system of claim 1, wherein the at least one
prime power system and the at least one energy storage system each
comprise: a generator operable to convert mechanical energy output
by the at least one prime power system into electrical energy; and
an electrical converter operable to convert the outputted generator
electrical energy into direct current electrical energy and to
permit electrical energy to flow reversibly in each of two
directions; wherein, at a selected time, the at least one prime
power system is turned off and the at least one energy storage
system is turned on, wherein the electrical converter of the at
least one energy storage system is switched to provide electrical
energy to the bus at a selected voltage level, and the electrical
converter of the at least one prime power system is switched to
receive electrical energy from the bus at the selected voltage
level, whereby the at least one prime power system is activated
using electrical energy supplied, via the bus, by the at least one
energy storage system.
14. The marine power system of claim 1, wherein the at least one
prime power system is located on a first vessel and the at least
one energy storage system is located on a second vessel being
displaced by the first vessel.
15. The marine power system of claim 14, wherein the first vessel
is a tugboat and the second vessel is a barge.
16. A marine power system comprising: i) at least one motor for
driving a propulsion unit having a propulsion unit average power
and a propulsion unit peak power; ii) at least one prime power
system driving a mechanical power system output shaft connected to
the at least one motor through a mechanical transmission; iii) at
least one alternator driven by the at least one prime power system
output shaft; iv) at least one energy storage unit for storing
electric energy and being connected to the at least one alternator,
having an energy storage capacity and an energy storage unit output
power; v) a bus electrically connecting the at least one energy
storage unit, and the at least one alternator; and vi) a control
system for controlling the operation of the at least one prime
power system and the propulsion unit, and for monitoring the at
least one energy storage unit, wherein the at least one energy
storage system provides starting power for the at least one prime
power system, and wherein the ratio of the at least one prime power
system rated power to the propulsion unit peak power is between 0.5
and 1.0.
17. The marine power system of claim 13, wherein the at least one
prime power system is located on a first vessel and the at least
one energy storage system is located on a second vessel being
displaced by the first vessel.
18. The marine power system of claim 17, wherein the first vessel
is a tugboat and the second vessel is a barge.
19. A method of storing energy in a marine vehicle comprising the
steps of: a) providing a marine power system comprising: i) at
least one motor for driving a propulsion unit having a propulsion
unit average power and a propulsion unit peak power; ii) at least
one energy storage unit for storing electric energy and supplying
said electric energy to said at least one motor, having an energy
storage capacity and an energy storage unit output power; iii) at
least one prime power system having a prime power system rated
power, being electrically connected to the at least one energy
storage unit and the at least one motor for selectively providing
electrical energy to the at least one energy storage unit and to
the at least one motor; iv) a bus electrically connecting the at
least one energy storage unit, the at least one prime power system
and the at least one motor; and v) a control system for controlling
the operation of the at least one prime power system and the
propulsion unit, and for monitoring the at least one energy storage
unit, b) selectively providing to the at least one motor
operational energy from the at least one energy storage unit and
the at least one prime power system; and c) supplying regenerative
braking energy from the at least one motor to the electrical bus
when the propulsion unit collects energy from water passing by the
propulsion unit, the ratio of the at least one prime power system
rated power to the propulsion unit peak power being between 0.1 and
0.8.
20. The method of storing energy in a marine vehicle according to
claim 19, wherein the at least one prime power system is located on
a first vessel and the at least one energy storage system is
located on a second vessel being displaced by the first vessel.
21. The marine power system of claim 1, further comprising at least
one supplementary regenerative braking power source electrically
connected to the bus and wherein the regenerative power source
supplies further regenerative braking energy to the bus.
22. The marine power system of claim 21, wherein the at least one
supplementary regenerative braking power source is selected from
the group consisting a winch system and a crane system.
Description
FIELD OF THE INVENTION
The present invention generally relates to an electrical
architecture for designing and operating a versatile marine power
system utilizing a plurality of engine, fuel, energy storage and
drive combinations. More particularly, the invention related to a
marine power train system and a method of storing energy in a
marine vehicle.
BACKGROUND OF THE INVENTION
Most older tug boats and other small marine vessels such as yachts
utilize a single inboard engine with a mechanical drive train to
operate a single screw. More modern tug boats now more commonly
have a single in-board engine with a mechanical drive train to
operate twin screws.
A so-called hybrid tug has a single engine but utilizes an
electrical transmission to drive twin screws. An electrical
transmission takes rectified ("DC") electrical output from an
alternator and drives a DC or AC motor which turns a screw. This is
directly analogous to a well-known diesel-electric locomotive power
train. In one configuration, two different size engines can be used
with an electrical transmission. The larger can be used, for
example, when more power or higher speeds are required and the
smaller engine can be used, for example, when less power and longer
range are required.
The Terra Nova Marine Company has developed a commercially viable
diesel-electric propulsion system for medium-sized fishing vessels
utilizing multiple engines. Electric motors replace the main diesel
propulsion engine so that the power production can be split to
several smaller diesel generators. Electric motors are highly
efficient over a range of operational speed and power output, while
a diesel engine has a clear peak in efficiency. They estimate that
the diesel-electric configuration will reduce emissions compared to
a similar vessel with a conventional propulsion system.
A jet drive is commonly used on some small marine craft. The jet
drive is comprised of an engine-driven water pump that sucks in
water through the bottom of the boat and shoots it out through a
nozzle at the stern. Steering the boat is done by changing the
direction of the discharge nozzle. A few of the advantages in using
a jet drive system are (1) a complete absence of all underwater
appendages--no rudder, no propeller, no strut, and no shaft; (2)
jet boats are safer around people in the water because of the lack
of all underwater appendages, especially the propeller; and (3)
because the system is so simple, there is less likelihood of
failure. Among the disadvantages of jet drives are that they are
still not as efficient as other systems and debris in the water
(weeds, trash, etc.) can be sucked into the pump and cause the
propulsion system to shut down.
Known to the applicant is WO1997/040999 which discloses a method
and apparatus for propelling a sail-powered marine vessel using
different power sources and power supplies.
There is an unmet need for a small marine craft drive architecture
that can utilize multiple engines, energy storage and use jet drive
technology for added maneuverability and regenerative braking.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a
marine power system comprising:
i) at least one motor for driving a propulsion unit having a
propulsion unit average power and a propulsion unit peak power;
ii) at least one energy storage unit for storing electric energy
and supplying said electric energy to the at least one motor,
having an energy storage capacity and an energy storage unit output
power;
iii) at least one prime power system having a prime power system
rated power, being electrically connected to the at least one
energy storage unit and the at least one motor for selectively
providing electrical energy to the at least one energy storage unit
and to the at least one motor;
iv) a bus electrically connecting the at least one energy storage
unit, the at least one prime power system and the at least one
motor; and
v) a control system for controlling the operation of the at least
one prime power system and the propulsion unit, and for monitoring
the at least one energy storage unit,
wherein the at least one motor selectively receives operational
energy from the at least one energy storage unit and the at least
one prime power system, the at least one motor supplies
regenerative braking energy to the bus when the propulsion unit
collects energy from water passing by the propulsion unit, and
wherein the ratio of the at least one prime power system rated
power to the propulsion unit peak power is between 0.1 and 0.8.
According to the present invention, there is also provided a marine
power system comprising:
i) at least one motor for driving a propulsion unit having a
propulsion unit average power and a propulsion unit peak power;
ii) at least one prime power system driving a mechanical power
system output shaft connected to the at least one motor through a
mechanical transmission;
iii) at least one alternator driven by the at least one prime power
system output shaft;
iv) at least one energy storage unit for storing electric energy
and being connected to the at least one alternator, having an
energy storage capacity and an energy storage unit output
power;
v) a bus electrically connecting the at least one energy storage
unit, and the at least one alternator; and
vi) a control system for controlling the operation of the at least
one prime power system and the propulsion unit, and for monitoring
the at least one energy storage unit,
wherein the at least one energy storage system provides starting
power for the at least one prime power system, and wherein the
ratio of the at least one prime power system rated power to the
propulsion unit peak power is between 0.5 and 1.0.
According to the present invention, there is also provided a method
of storing energy in a marine vehicle comprising the steps of:
a) providing a marine power system comprising:
i) at least one motor for driving a propulsion unit having a
propulsion unit average power and a propulsion unit peak power;
ii) at least one energy storage unit for storing electric energy
and supplying said electric energy to said at least one motor,
having an energy storage capacity and an energy storage unit output
power;
iii) at least one prime power system having a prime power system
rated power, being electrically connected to the at least one
energy storage unit and the at least one motor for selectively
providing electrical energy to the at least one energy storage unit
and to the at least one motor;
iv) a bus electrically connecting the at least one energy storage
unit, the at least one prime power system and the at least one
motor; and
v) a control system for controlling the operation of the at least
one prime power system and the propulsion unit, and for monitoring
the at least one energy storage unit,
b) selectively providing to the at least one motor operational
energy from the at least one energy storage unit and the at least
one prime power system; and
c) supplying regenerative braking energy from the at least one
motor to the electrical bus when the propulsion unit collects
energy from water passing by the propulsion unit,
the ratio of the at least one prime power system rated power to the
propulsion unit peak power being between 0.1 and 0.8.
These and other needs are addressed by the various embodiments and
configurations of the present invention which are directed
generally to design and control of individual prime power systems
of a multi-prime power source marine propulsion system.
The inventions disclosed herein are applicable to marine craft such
as tugboats, fishing boats, barges, yachts and other small to
medium size marine craft that can utilize multiple prime power
sources such as diesel engines, gas turbine engines, fuel cells,
other types of internal combustion engines or combinations of these
along with an energy storage units. The inventions disclosed herein
are also applicable to such marine craft utilizing multiple prime
power sources, energy storage units and water jet propulsion
systems.
In one embodiment, a number of small engines are used in
conjunction with an electric transmission to operate one or more
motors that directly turn one or more screws. In this embodiment,
the engines can be placed so as to optimize ballast requirements
and allow ready servicing and replacement of engines. The engines
may be of similar types and sizes or dissimilar types and
dissimilar sizes. For example, the engines may be diesel engines,
gas turbine engines, fuel cells, other types of internal combustion
engines or combinations of these.
In a second embodiment, the power system may be comprised of one or
more engines and an energy storage system. The energy storage
system can be charged by one or more of the engines. The energy
storage system may be used to provide all the power for propulsion
such as for example when moving about a marina or small harbor. The
energy storage system may also be used to provide auxiliary power
when all the engines are on or off. The energy storage system may
also be used to provide an additional power boost when one or all
of the engines are operating. The energy storage system may be a
battery pack, a capacitor bank, a flywheel system or a combination
of these.
In a third embodiment, the power system may be comprised of one or
more engines, an energy storage system and a jet propulsion drive.
The jet drive may be used to augment propulsion or to provide
additional mobility when used as side thrusters. If the jet drive
pump is operated as a turbine and the jet drive motor is operated
as a generator, the system may also be used to provide dynamic or
regenerative braking for the craft. In braking mode, incoming water
is used to operate a turbine which in turn operates a generator.
Kinetic energy is removed from the water and the water pressure on
the upstream side of the turbine is greater than the water pressure
on the downstream side, thereby providing a braking force to the
craft. The energy generated by this system can be dissipated in a
resistive grid (dynamic braking) or used to charge an energy
storage system (regenerative braking).
The above embodiments allow a number of additional techniques to be
applied. For example, the present invention can utilize a means of
boosting the voltage output of an alternator utilizing the armature
coils of the alternator as part of the boost circuit. This
invention can enable refined control strategies for operating a
plurality of engine systems during propulsion, idling and braking
and is applicable to marine craft utilizing diesel engines, gas
turbine engines, other types of internal combustion engines, fuel
cells or combinations of these that require substantial power and
low emissions utilizing multiple power plant combinations.
As another example, the present invention can utilize a number of
control strategies for operating a plurality of prime power sources
during propulsion, idling and braking and is applicable to marine
propulsion systems utilizing diesel engines, gas turbine engines,
other types of internal combustion engines, fuel cells or
combinations of these that require substantial power and low
emissions utilizing multiple power plant combinations. The present
invention is directed at a general control strategy for multi-power
plant systems where the power systems need not be of the same type
or power rating and may even use different fuels. The invention is
based on a common DC bus electrical architecture so that prime
power sources need not be synchronized.
As another example, the present invention can utilize a means of
starting or restarting an engine on a marine craft having at least
one of another engine, a fuel cell system and an energy storage
system. The method is applicable to propulsion systems utilizing
diesel engines, gas turbine engines, other types of internal
combustion engines, fuel cells or combinations of these that
require substantial power and low emissions utilizing multiple
power plant combinations.
The present invention is directed, in part, at a flexible control
strategy for a multi-engine systems based on a common DC bus
electrical architecture so that prime power sources need not be
synchronized.
Another benefit of this invention is the capacity to recharge the
energy storage system by an electrical power line. This power line
can be fed by a power source on shore or on another vessel.
Another aspect of the present invention involves energy and power
transfer amongst different crafts such as might be advantageous to
a hybrid tugboat pushing or pulling a hybrid barge or string of
barges.
It is understood that a reference to specific marine craft such as
tugboats, fishing boats, barges, yachts and other small to medium
size marine craft applies to all these types of small to medium
size marine craft unless otherwise stated.
These and other advantages will be apparent from the disclosure of
the invention(s) contained herein.
The above-described embodiments and configurations are neither
complete nor exhaustive. As will be appreciated, other embodiments
of the invention are possible utilizing, alone or in combination,
one or more of the features set forth above or described in detail
below.
The following definitions are used herein:
A hybrid vehicle combines an energy storage system, a prime power
unit, and a vehicle propulsion system. A parallel hybrid vehicle is
configured so that propulsive power can be provided by the prime
power source only, the energy storage source only, or both. In a
series hybrid vehicle, propulsive power is provided by the energy
storage unit only and the prime power source is used to supply
energy to the energy storage unit.
When the energy storage capacity is small and the prime power
source is large, the hybrid may be referred to as a power-assist
hybrid. For example, an electric drive may be used primarily for
starting and power assist while an internal combustion engine used
primarily for propulsion. These vehicles are typically parallel
hybrids.
In a dual-mode hybrid, the energy storage and prime power are
approximately balanced. For example, a dual-mode hybrid can operate
on electric drive only, on engine power only, or on a combination
of both. These vehicles are typically parallel hybrids.
A range-extended hybrid has a large energy storage capacity and a
small prime power source. An example would be an electric drive
vehicle with a small engine used for charging an electrical energy
storage unit. These vehicles are typically series hybrids.
An engine refers to any device that uses energy to develop
mechanical power, such as motion in some other machine. Examples
are diesel engines, gas turbine engines, microturbines, Stirling
engines and spark ignition engines.
A prime power source refers to any device that uses energy to
develop mechanical or electrical power, such as motion in some
other machine. Examples are diesel engines, gas turbine engines,
micro-turbines, Stirling engines, spark ignition engines or fuel
cells.
A motor refers to a device that produces or imparts motion.
A traction motor is a motor used primarily for propulsion such as
commonly used in a locomotive. Examples are an AC or DC induction
motor, a permanent magnet motor and a switched reluctance
motor.
An energy storage system refers to any apparatus that acquires,
stores and distributes mechanical or electrical energy which is
produced from another energy source such as a prime energy source,
a regenerative braking system, a third rail and a catenary and any
external source of electrical energy. Examples are a battery pack,
a bank of capacitors, a compressed air storage system, a hydraulic
accumulator and a bank of flywheels.
An electrical energy converter refers to an apparatus that
transmits or blocks the flow of electrical energy and may also
increase or reduce voltage and change the frequency of the
transmitted energy including changing the frequency to zero.
Examples but are not limited to an inverter, a rectifier circuit, a
chopper circuit, a controlled rectifier such as a cycle converter,
a boost circuit, a buck circuit and a buck/boost circuit.
A mechanical-to-electrical energy conversion device refers an
apparatus that converts mechanical energy to electrical energy.
Examples include but are not limited to a synchronous alternator
such as a wound rotor alternator or a permanent magnet machine, an
asynchronous alternator such as an induction alternator, a DC
generator, and a switched reluctance generator.
Dynamic braking is implemented when the electric propulsion motors
are switched to generator mode during braking to augment the
braking force. The electrical energy generated is typically
dissipated in a resistance grid system.
Regenerative braking is the same as dynamic braking except the
electrical energy generated is recaptured and stored in an energy
storage system for future use.
Engine speed is the rotary speed of the engine output drive shaft
and is typically expressed in rpms.
Alternator speed is the rotary speed of the alternator rotor and is
typically expressed in rpms. The alternator speed is commonly the
same as engine speed since they are usually directly connected with
no intermediate gearing.
An IGBT is Insulated Gate Bipolar Transistor which is a power
switching device capable of sequentially chopping a voltage
waveform at a very fast rate.
The duty cycle of an IGBT is the ratio of time that the IGBT is
switched on (conducting) to the total time that the IGBT is
switched on (conducting) and off (non-conducting).
As used herein, "at least one", "one or more", and "and/or" are
open-ended expressions that are both conjunctive and disjunctive in
operation. For example, each of the expressions "at least one of A,
B and C", "at least one of A, B, or C", "one or more of A, B, and
C", "one or more of A, B, or C" and "A, B, and/or C" means A alone,
B alone, C alone, A and B together, A and C together, B and C
together, or A, B and C together.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the invention will become
apparent upon reading the detailed description and upon referring
to the drawings in which:
FIG. 1 is a schematic block diagram of a propulsion system for a
hybrid marine craft.
FIG. 2 is a schematic circuit diagram of a propulsion system for a
hybrid marine craft.
FIG. 3 is a schematic block diagram of a propulsion system for a
multi-engine hybrid marine craft.
FIG. 4 is a schematic block diagram of an alternate propulsion
system for a multiengine hybrid marine craft.
FIG. 5 is a schematic circuit diagram of an alternate propulsion
system for a multiengine hybrid marine craft.
FIG. 6 is a schematic block diagram of a propulsion system for a
multi-engine marine craft with a hybrid auxiliary power system.
FIG. 7 is a schematic circuit diagram for a multi-engine hybrid
marine craft with a hybrid auxiliary power system.
FIG. 8 is a schematic block diagram of an alternate propulsion
system for a multiengine hybrid marine craft with a hybrid
auxiliary power system.
FIG. 9 is a schematic block diagram of a jet propulsion system for
a hybrid barge with regenerative braking.
FIG. 10 is a schematic plan view of a barge with a jet propulsion
system in motoring mode.
FIG. 11 is a schematic plan view of a barge with a jet propulsion
system in braking mode.
FIG. 12 is a schematic block diagram of a hybrid tugboat exchanging
power with a hybrid barge.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1, according to the present invention, there is
provided a marine power system comprising:
i) at least one motor 124 for driving a propulsion unit 125 having
a propulsion unit average power and a propulsion unit peak
power;
ii) at least one energy storage unit 105 for storing electric
energy and supplying said electric energy to the at least one motor
124, having an energy storage capacity and an energy storage unit
output power;
iii) at least one prime power system 101 having a prime power
system rated power, being electrically connected to the at least
one energy storage unit 105 and the at least one motor 124 for
selectively providing electrical energy to the at least one energy
storage unit 105 and to the at least one motor 124;
iv) a bus 110 electrically connecting the at least one energy
storage unit 105, the at least one prime power system 101 and the
at least one motor 124; and
v) a control system for controlling the operation of the at least
one prime power system 101 and the propulsion unit 125, and for
monitoring the at least one energy storage unit 105,
wherein the at least one motor 124 selectively receives operational
energy from the at least one energy storage unit 105 and the at
least one prime power system 101, the at least one motor 124
supplies regenerative braking energy to the bus 110 when the
propulsion unit 125 collects energy from water passing by the
propulsion unit 125, and wherein the ratio of the at least one
prime power system rated power to the propulsion unit peak power is
between 0.1 and 0.8.
For example, in the case of a 5000 hp hybrid marine power system in
series, up to 10 500 hp generators may be required to use Tier 3 or
Tier 4 optimized off-road engines. In another case, a 4000 hp
generator may be used in conjunction with a 1000 hp energy storage
system.
Preferably, the marine power system further comprises an alternator
driven by the at least one prime power system, the alternator being
electrically connected to the bus, wherein the at least one energy
storage system provides starting power for the at least one prime
power system.
Preferably, the marine power system further comprises a plurality
of electrical energy converters operable to convert energy to
electrical energy having a desired electrical characteristic, the
plurality of electrical energy converters comprising first and
second electrical energy converters having respectively first and
second output voltages and first and second output currents, the
plurality of electrical energy converters being electrically
connected to the bus. A plurality of prime power systems provide
energy to the plurality of electrical energy converters, the
plurality of prime power systems comprising first and second
engines corresponding respectively to the first and second
electrical energy converters. The bus is operable to transport
electrical energy from the electrical energy converters to the at
least one motor. At a selected time, the relationship between at
least one of a current level and a voltage level of the bus on the
one hand and at least one of the first and second output currents
and the first and second output voltages of the first and second
electrical energy converters on the other hand determines, at the
selected time, which of the first and second engines supplies
energy to the bus through the corresponding electrical energy
converter.
Preferably, the at least one prime power system comprises a prime
power source selected from the group consisting of engines, diesel
engines, gas turbine engines, microturbines, Stirling engines,
spark ignition engines, fuel cells, solar cells, grid power, power
induction systems, wind turbines and a combination thereof.
Preferably, the energy storage unit comprises an energy storage
system selected from the group consisting of a battery pack, a bank
of capacitors, a compressed air storage system, a hydraulic
accumulator, one or more flywheels and a combination thereof.
Preferably, the energy storage unit forms part of a ballast in a
marine vehicle.
Preferably, the system further comprises a power-dissipating load
for dissipating excess regenerative braking energy on the
electrical bus, and the power-dissipating load is mounted on a
marine vehicle under water.
Preferably, the system further comprises an auxiliary power system
connected to the electrical bus.
Preferably, the control system comprises a controller selected from
the group consisting of analog devices, programmable logic
controllers and computers.
Preferably, the at least one energy storage unit and the at least
one prime power system are sized and provided in a form adapted to
retrofit with an existing receiving means on a marine vehicle for
receiving a diesel engine and a generator set.
Preferably, the at least one energy storage unit provides power
regulation to the at least one prime power system.
Preferably, the propulsion unit comprises a drive system selected
from the group consisting of screws, propellers, and jet pumps.
Preferably, the at least one prime power system and the at least
one energy storage system each comprise: a generator operable to
convert mechanical energy output by the at least one prime power
system into electrical energy; and an electrical converter operable
to convert the outputted generator electrical energy into direct
current electrical energy and to permit electrical energy to flow
reversibly in each of two directions.
At a selected time, the at least one prime power system is turned
off and the at least one energy storage system is turned on. The
electrical converter of the at least one energy storage system is
switched to provide electrical energy to the bus at a selected
voltage level. The electrical converter of the at least one prime
power system is switched to receive electrical energy from the bus
at the selected voltage level. The at least one prime power system
is activated using electrical energy supplied, via the bus, by the
at least one energy storage system.
Preferably, the at least one prime power system is located on a
first vessel and the at least one energy storage system is located
on a second vessel being displaced or towed by the first
vessel.
Preferably, the first vessel is a tugboat and the second vessel is
a barge.
According to the present invention, there is also provide a marine
power system comprising:
i) at least one motor for driving a propulsion unit having a
propulsion unit average power and a propulsion unit peak power;
ii) at least one prime power system driving a mechanical power
system output shaft connected to the at least one motor through a
mechanical transmission;
iii) at least one alternator driven by the at least one prime power
system output shaft;
iv) at least one energy storage unit for storing electric energy
and being connected to the at least one alternator, having an
energy storage capacity and an energy storage unit output
power;
v) a bus electrically connecting the at least one energy storage
unit, and the at least one alternator; and
vi) a control system for controlling the operation of the at least
one prime power system and the propulsion unit, and for monitoring
the at least one energy storage unit,
wherein the at least one energy storage system provides starting
power for the at least one prime power system, and wherein the
ratio of the at least one prime power system rated power to the
propulsion unit peak power is between 0.5 and 1.0.
For example, in the case of a 4000 hp hybrid marine parallel power
system, a 2000 hp motor may be used with a 2000 hp energy storage
subsystem or an auxiliary multi-generator set. In another case, the
motor must provide the complete 4000 hp with the energy storage
system or auxiliary multi-generator set only operating when the
system is in standby mode.
Preferably, the marine power system of claim further comprises a
supplementary regenerative braking power source electrically
connected to the bus. The supplementary regenerative power source
supplies further regenerative braking energy to the bus.
Preferably, the supplementary regenerative braking power source is
selected from the group consisting a winch system and a crane
system.
According to the present invention, there is also provide a method
of storing energy in a marine vehicle comprising the steps of:
a) providing a marine power system comprising:
i) at least one motor for driving a propulsion unit having a
propulsion unit average power and a propulsion unit peak power;
ii) at least one energy storage unit for storing electric energy
and supplying said electric energy to said at least one motor,
having an energy storage capacity and an energy storage unit output
power;
iii) at least one prime power system having a prime power system
rated power, being electrically connected to the at least one
energy storage unit and the at least one motor for selectively
providing electrical energy to the at least one energy storage unit
and to the at least one motor;
iv) a bus electrically connecting the at least one energy storage
unit, the at least one prime power system and the at least one
motor; and
v) a control system for controlling the operation of the at least
one prime power system and the propulsion unit, and for monitoring
the at least one energy storage unit,
b) selectively providing to the at least one motor operational
energy from the at least one energy storage unit and the at least
one prime power system; and
c) supplying regenerative braking energy from the at least one
motor to the electrical bus when the propulsion unit collects
energy from water passing by the propulsion unit,
the ratio of the at least one prime power system rated power to the
propulsion unit peak power being between 0.1 and 0.8.
The marine power system may also use systems or power architectures
described in the following references, the contents of which are
incorporated herein by reference: "Alternator Boost Method", filed
Apr. 25, 2006 with U.S. Ser. No. 11/411,987, "Locomotive Power
Train Architecture", filed Aug. 19, 2005 with U.S. Ser. No.
11/200,881, "Hybrid Locomotive Configuration", filed Mar. 8, 2005
with U.S. Ser. No. 11/075,550, "Multiple Prime Power Source
Locomotive Control", filed Apr. 25, 2006 with U.S. Ser. No.
11/412,071, "Locomotive Engine Start Method", filed Apr. 25, 2006
with U.S. Ser. No. 11/411,986, and "Multi-Power Source Locomotive
Control Modes", filed Jun. 15, 2006 with U.S. Ser. No.
60/814,595.
FIG. 1 is a schematic block diagram of a propulsion system for a
hybrid marine craft comprised of a single engine 101 and an energy
storage unit 105 connected in parallel to a direct current ("DC")
bus represented by a positive bus bar 110 and a negative bus bar
111. The engine is the prime power source in the propulsion system.
Examples are diesel engines, gas turbine engines, micro-turbines,
Stirling engines, spark ignition engines or fuel cells. The
mechanical shaft 102 of engine 101 drives an alternator 103 whose
alternating current ("AC") output is rectified by rectifier circuit
104 which is in turn connected to the DC bus. The
alternator/rectifier combination can be formed from, for example, a
synchronous alternator such as a wound rotor alternator or a
permanent magnet machine, an asynchronous alternator such as an
induction alternator, a DC generator, and a switched reluctance
generator. An auxiliary power supply 122 for the craft is shown
connected to the DC bus by a voltage reduction apparatus 121 which
may be, for example, a voltage buck circuit. In this example, two
propulsion units each turning its own screw (propeller) 125 are
shown. Propulsion motors 124 are shown connected in parallel to the
DC bus, each via an electrical energy converter 123 which is an
inverter when propulsion motor 124 is an AC motor and a chopper
circuit when propulsion motor 124 is a DC motor.
FIG. 2 is a schematic circuit diagram of a propulsion system for a
hybrid marine craft with an engine represented by alternator 201.
Engine 201 is shown with voltage boost alternator/rectifiers 202
such as described in "Alternator Boost Method", Donnelly and
Tarnow, filed Apr. 25, 2006 with U.S. Ser. No. 11/411,987. The
alternator 201 is taken to be a 3-phase alternator and the engine
output shaft is taken to be directly connected to the rotor of the
alternator (so engine rpms and alternator rpms are the same in the
examples discussed herein). As can be appreciated, the alternator
can be a 2-phase or n-phase machine but is typically a 3-phase
machine when used with large diesel engines such as used on marine
craft, for example. As can also be appreciated, the engine output
shaft can be geared up or down to couple with the alternator rotor.
However, in most diesel-electric locomotives, the engine output
shaft is directly connected to the rotor of the alternator. When
the engine is operating at high rpm, there is no need to boost the
output voltage of the alternator/rectifier. However, when the
engine is operating at low rpm, the exciter circuit cannot
sufficiently compensate to provide the required level of output
voltage. At low rpm, for example at 1,000 rpm (where the preferred
operating rpm level of the alternator is in the range of about
1,700 to about 1,900 rpm), the output frequency of each armature
coil is about 33 Hz. A power IGBT can operate at on/off frequencies
of about 1,000 Hz and so can provide the requisite pumping action
to boost the output voltage of each armature coil. That is, the
inductance of the alternator armature coils is in the correct range
for effective voltage boost for the range of alternator operating
frequencies and the available IGBT switching duty cycles. A battery
pack 203 is shown connected in parallel to a DC bus represented by
a positive bus bar 210 and a negative bus bar 211 via a buck/boost
circuit 204. The buck/boost circuit can be used to control the
voltage level supplied to the DC bus. This is an optional feature
but could be used, for example, to boost the voltage of a battery
pack when the state-of-charge ("SOC") is low. An auxiliary power
supply system 221 is shown connected to the DC bus by a voltage
buck circuit. Typically, the voltage on the DC bus is in the
approximately 400 to 800 volt range and this level must be reduced
for most common marine auxiliary power systems. Two propulsion
motor systems 223 are shown attached to the DC bus where the
propulsion systems are shown here, for example, as series wound DC
motors with field coil reversers and chopper controlled
freewheeling circuits.
FIG. 3 is a schematic block diagram of a propulsion system for a
multi-engine hybrid marine craft comprised of a three engines 301
and an energy storage unit 305 connected in parallel to a DC bus
represented by a positive bus bar 310 and a negative bus bar 311.
The engines are the prime power sources in the propulsion system.
The mechanical shafts 302 of engines 301 drive alternators 303
whose AC output is rectified by rectifier circuits 304 which are in
turn connected to the DC bus. An auxiliary power supply 322 for the
craft is shown connected to the DC bus by a voltage reduction
apparatus 321. In this example, two propulsion units each turning
its own screw 325 are shown. Propulsion motors 324 are shown
connected in parallel to the DC bus, each via an electrical energy
converter 323 which is an inverter when propulsion motor 324 is an
AC motor and a chopper circuit when propulsion motor 324 is an DC
motor. An advantage of this configuration over that of the single
engine hybrid shown in FIG. 1 is that the 3 engines can have the
same total power as the single engine of the configuration shown in
FIG. 1. This allows more efficient fuel management in many
situations such as transition from high speed to low speed or, in
the case of a tugboat, transition from high speed to low speed at
high power. Another advantage of this configuration over that of
the single engine hybrid is the ability to place the engines and
energy storage unit so as to optimize the ballast distribution of
the craft. Yet another advantage of this configuration over that of
the single engine hybrid, is the greater ease of serviceability
including removal and replacement of smaller engines over that of a
single large engine.
FIG. 4 is a schematic block diagram of an alternate propulsion
system for a multiengine hybrid marine craft. In the configuration
shown in FIG. 3, the 3 engine systems are shown connected in
parallel to the DC bus (an engine system as used herein refers to
the engine and its alternator/rectifier circuits). As can be
appreciated, the engine systems need not be synchronized since they
are providing DC power to the DC bus and each engine system has
some range of independent voltage control. As shown in FIG. 4, the
3 engine systems are connected in series. Again, the engine systems
need not be synchronized since they are providing DC power at their
outputs. Each engine system can be operated at its own voltage
output level although the current is common to all the engine
systems. Otherwise the propulsion system is shown as being the same
as that of FIGS. 1 and 3. This configuration is comprised of a
three series connected engine systems and an energy storage unit
405 connected in parallel to a DC bus represented by a positive bus
bar 310 and a negative bus bar 311. The mechanical shafts 402 of
engines 401 drive alternators 403 whose AC output is rectified by
rectifier circuits 404 which are in turn connected in series by
connections 405 to the DC bus. An auxiliary power supply 421 for
the craft is shown connected to the DC bus by a voltage reduction
apparatus. In this example, two propulsion units 422 each turning
its own screw are shown.
FIG. 5 is a schematic circuit diagram of the series connected
engines in the alternate propulsion system of FIG. 4. Three-phase
alternators 501 are shown along with their excitation coils 502.
The AC outputs of each alternator 501 are connected to a rectifier
circuit 503. The leftmost alternator/rectifier output is connected
to the positive side 510 of the bus bar and to the middle
alternator/rectifier by connection 504. The other output of the
middle alternator/rectifier is connected to the rightmost
alternator/rectifier by connection 505, by connection 504. Finally,
the rightmost alternator/rectifier output is connected to the
negative side 511 of the bus bar. The voltage V-bus applied to the
DC bus is the sum of the individual alternator/rectifier outputs
V1, V2 and V3. This series connected configuration of engines can
be applied to other multi-engine vehicles such as for example
multi-engine locomotives and multi-engine gantry cranes.
FIG. 6 is a schematic block diagram of a propulsion system for a
multi-engine marine craft with a hybrid auxiliary power system. In
this configuration, three engines 601 are used. Each engine 601
drives a flywheel starter alternator which is comprised of
typically a smaller alternator 603 which feeds power to an
auxiliary power system DC bus and typically larger alternator 606
which feeds power to a main propulsion DC bus. Alternators 603 and
606 are driven by the output shaft of engine 601 shown as shafts
602 and 604. The main propulsion DC bus represented by bus bars 610
and 611 receives DC power from rectifier circuits 607 and are shown
here driving a twin screw propulsion system 621, each of which is
comprised of an electrical energy converter, a motor and a screw.
The auxiliary power system DC bus represented by bus bars 630 and
631 receives DC power from rectifier circuits 605 and are shown
here providing power to an energy storage system 642 and an
auxiliary power system 641. As can be seen, the main propulsion DC
bus can be operated at a different voltage and power level
(typically higher) than the auxiliary power system DC bus
(typically lower). The auxiliary power system DC bus system can be
operated from the energy storage system alone such as for example
when the craft is in harbor and requires lighting, heating or
air-conditioning for example. The energy storage system can be
recharged by plugging into a power source on shore, on another
vessel or from the engines 601 when idling or providing power to
the main propulsion DC bus.
A conventional battery operated starter motor can be used to start
an engine. Alternately, the voltage control strategy articulated
above is also compatible with the use of an induction alternator to
provide electrical power from the engine or engines to a DC bus.
The use of an induction alternator, when at least one electrical
power source is in operation supplying power to the DC bus, would
allow power from the DC bus to be used to start or restart an
engine that is turned off. This method of starting engines is known
and is used to provide high starting power without the need of a
separate starter motor. A pre-lubrication pump can also be operated
directly from the DC bus or from an auxiliary power supply to
lubricate a diesel engine just prior to starting it so as to extend
its operational lifetime. While the above engine start-up
procedures are well-known, they can be applied more readily
utilizing the voltage control and DC bus architecture of the
present invention.
FIG. 7 is a schematic circuit diagram for a multi-engine hybrid
marine craft with a hybrid auxiliary power system. In this
configuration, three engines systems 701 are used. Each engine
drives a flywheel starter alternator which is comprised of a
typically smaller alternator 704 which feeds power to an auxiliary
power system DC bus via an induction alternator and converter
system 705; and a typically larger alternator 702 which feeds power
to a main propulsion DC bus via diode rectifier system 703. The
main propulsion DC bus represented by bus bars 710 and 711 receives
DC power from rectifier circuits 703 and are shown here driving two
twin screw propulsion systems 721 and 722, each of which shown
here, for example, as series wound DC motors with field coil
reversers and chopper controlled free wheeling circuits.
Engine systems 704 are shown with induction alternator and
converter systems 705. The alternator and converter systems 705
allow energy and power to flow to or from the auxiliary power DC
bus. The battery pack 741 may be used to provide power for starting
one or more engines 704 by any of a number of well-known methods.
As can be appreciated, the energy storage system 741 can also be a
capacitor bank or a flywheel storage system. A similar electrical
architecture for a multi-engine locomotive was disclosed previously
in U.S. patent application Ser. No. 11/200,881 filed Aug. 19, 2005
entitled "Locomotive Power Train Architecture".
The auxiliary power system DC bus represented by bus bars 730 and
731 receives DC power from alternator and converter systems 705 and
are shown here providing power to an energy storage system 741 and
its optional voltage buck/boost circuit 742; and an auxiliary power
system 743 and its optional voltage boost circuit 744. As can be
seen, the main propulsion DC bus can be operated at a different
voltage and power level (typically higher) than the auxiliary power
system DC bus (typically lower). As described previously, the
auxiliary power system DC bus system can be operated from the
energy storage system alone.
FIG. 8 is a schematic block diagram of an alternate propulsion
system for a multiengine hybrid marine craft with a hybrid
auxiliary power system and is similar to the configuration shown in
FIG. 6 except that the main propulsion system is driven by a
mechanical transmission rather than by an electrical transmission.
In this configuration, three engines 801 are used. Each engine 801
drives a flywheel starter alternator which is comprised of
typically an alternator 805 driven by the engine output shaft 802
which feeds power to an auxiliary power system DC bus. Engine
output shaft 804 is connected to a mechanical transmission 806 and
is shown here driving a twin screw 807 propulsion system.
The transmission 806 may be a synchronous transmission which would
require the engines 801 to be operated synchronously or the
transmission 806 may be comprised of differential elements which
would allow the engines 801 to be operated asynchronously. The
auxiliary power system DC bus represented by bus bars 810 and 811
receives DC power from alternator and converter systems 805 and are
shown here providing power to an energy storage system 822 and an
auxiliary power system 821. The auxiliary power system DC bus
system can be operated from the energy storage system alone such as
for example when the craft is in harbor and requires lighting,
heating or air-conditioning for example. The energy storage system
can be recharged by plugging into a power source on shore, on
another vessel or from the engines 801 when idling or providing
power to the main propulsion system.
Engine systems 801 are shown with induction alternator and
converter systems 805. The alternator and converter systems 805
allow energy and power to flow to or from the auxiliary power DC
bus. The energy storage system 822 may be used to provide power for
starting one or more engines 801 by any of a number of well-known
methods. As can be appreciated, the energy storage system 822 can
be a battery pack, capacitor bank or a flywheel energy storage
system.
FIG. 9 is a schematic block diagram of a jet propulsion system for
a hybrid barge with regenerative braking. In this configuration,
three engines 901 and an energy storage unit 905 connected in
parallel to a DC bus represented by a positive bus bar 910 and a
negative bus bar 911. The engines are the prime power sources in
the propulsion system. Mechanical shafts 902 of engines 901 drive
alternators 903 whose AC output is rectified by rectifier circuits
904 which are in turn connected to the DC bus. An auxiliary power
supply 921 for the craft is shown connected to the DC bus by a
voltage reduction apparatus. A dissipating electrical grid 930 is
also shown connected to the DC bus and is used for dynamic braking
when switch 931 is closed. In this example, two propulsion units
each providing water jet thrust from its own thruster 925 are
shown. Propulsion motors 923 and pumps 924 are shown connected in
parallel to the DC bus, each via an electrical energy converter 922
which is an inverter when propulsion motor 923 is an AC motor and a
chopper circuit when propulsion motor 923 is an DC motor. In
propulsion mode, the motors 923 provide power to the pumps 924
which energize water to provide propulsive and/or steering thrust
via thrusters 925 as is well known in marine jet propulsion
systems. In braking mode, the pumps 924 are operated as turbines
which in turn operate the motors 923 as generators to provide
electrical power back to the DC bus. The electrical circuits
capable of providing dynamic and/or regenerative braking action are
described in "Regenerative Braking Methods for a Hybrid
Locomotive", Donnelly et al, filed Aug. 9, 2005 as U.S. Ser. No.
11/200,879 and in "Dynamic Braking for a Hybrid Locomotive",
Donnelly and Tarnow, filed Apr. 19, 2006 as U.S. Provisional
60/745,153, both of which are incorporated herein by reference.
In braking mode, the pumps are operated as turbines and extract
energy from the water entering the forward inlet. This extracted
energy can converted into electrical energy and stored energy in
the energy storage system such as, for example, a battery pack or a
capacitor bank. If no energy storage capacity is available, the
energy can be dissipated in an electrically resistive grid such as
used on diesel locomotives with dynamic braking. Such as
dissipating grid can be mounted on the craft under water so that it
can be cooled by water through well-known heat exchanger
methods.
In braking mode, when the water enters the inlet, the turbines
extract energy from the water and cause a back pressure that
results in less water flowing through the system and a net
retarding force acting to slow the craft.
FIG. 10 is a schematic plan view of a barge such as described above
with a jet propulsion system in motoring mode. Water 1004 enters
the forward inlets 1003 and is energized by pump 1002 and then is
propelled out of the main propulsion nozzles 1005, which are above
the water line, as a high velocity stream of water 1006 to provide
propulsive thrust. The energized water may also be directed by
switching large valves to direct the propulsive water discharge
through side ports 1007 and 1008 to provide a sideways thrust or a
steering thrust, depending on which side thrusting ports are
activated. A high velocity water stream 1008 would tend to swing
the rear of the barge towards the top of the page. A high velocity
water stream 1010 would tend to swing the front of the barge
towards the top of the page. High velocity water streams 1008 and
1010 simultaneously would tend to move the entire barge sideways
towards the top of the page.
FIG. 11 is a schematic plan view of a barge with a jet propulsion
system in braking mode. Water 1103 enters the forward inlets 1102
and is de-energized by the pump now acting as a turbine. The
de-energized water is then discharged at low velocity out of the
main propulsion nozzles or through the side ports.
FIG. 12 is a schematic block diagram of a hybrid tugboat exchanging
power with a hybrid barge. This figure shows a schematic block
diagram of a propulsion system for a multiengine hybrid marine
tugboat 1201 craft comprised of a three engines 1202 and an energy
storage unit 1203 connected in parallel to a DC bus represented by
a positive bus bar 1210 and a negative bus bar 1211. An auxiliary
power supply 1205 and two propulsion units 1204 each turning its
own screw are shown connected in to the DC bus. Tugboat 1201 is
similar to the craft illustrated in FIG. 3.
This figure also shows a schematic block diagram of a propulsion
system for a hybrid barge comprised of a single engine 1222 and an
energy storage unit 1223 connected in parallel to the DC bus
represented by a positive bus bar 1210 and a negative bus bar 1211.
An auxiliary power supply 1225 for the barge and two propulsion
units 1224 each turning its own screw are also shown. The tug DC
buses of the and the barge are electrically connected as shown so
that energy and power can be exchanged between the two craft.
For example, the barge can have a modest size engine 1222 and a
large energy storage unit 1223 which would allow it to move about
at low speeds near its point of loading and unloading. The engine
1222 and energy storage system 1223 can be used, for example, to
allow the barge to dump or assist in unloading as well as
maneuvering into position. The energy storage system 1223 alone can
be used to operate the auxiliary power system 1225. When required,
the energy storage system 1223 can be charged by the engine
1222.
The tug, for example, may have two large engines 1202 and a
moderate size energy storage unit 1203. With the tug 1201 and barge
1221 electrically connected, the tug can provide most of the
propulsion power with its two engines 1202 and can increase
propulsive power when needed by controlling the propulsion system
of the barge which, because of its large energy storage system
1223, can generate a large surge of propulsive power with little or
no lag time. Alternately, the tug can slow the barge down more
effectively by reversing the direction of its twin screws at full
power and control the barge to reverse its twin screws with a large
surge of propulsive power from its energy storage unit 1223 again
with little or no lag time.
The present invention, in various embodiments, includes components,
methods, processes, systems and/or apparatus substantially as
depicted and described herein, including various embodiments,
sub-combinations, and subsets thereof. Those of skill in the art
will understand how to make and use the present invention after
understanding the present disclosure. The present invention, in
various embodiments, includes providing devices and processes in
the absence of items not depicted and/or described herein or in
various embodiments hereof, including in the absence of such items
as may have been used in previous devices or processes, for example
for improving performance, achieving ease and\or reducing cost of
implementation. The foregoing discussion of the invention has been
presented for purposes of illustration and description. The
foregoing is not intended to limit the invention to the form or
forms disclosed herein. In the foregoing Detailed Description for
example, various features of the invention are grouped together in
one or more embodiments for the purpose of streamlining the
disclosure. This method of disclosure is not to be interpreted as
reflecting an intention that the claimed invention requires more
features than are expressly recited in each claim. Rather, as the
following claims reflect, inventive aspects lie in less than all
features of a single foregoing disclosed embodiment. Thus, the
following claims are hereby incorporated into this Detailed
Description, with each claim standing on its own as a separate
preferred embodiment of the invention. Moreover though the
description of the invention has included description of one or
more embodiments and certain variations and modifications, other
variations and modifications are within the scope of the invention,
e.g., as may be within the skill and knowledge of those in the art,
after understanding the present disclosure. It is intended to
obtain rights which include alternative embodiments to the extent
permitted, including alternate, interchangeable and/or equivalent
structures, functions, ranges or steps to those claimed, whether or
not such alternate, interchangeable and/or equivalent structures,
functions, ranges or steps are disclosed herein, and without
intending to publicly dedicate any patentable subject matter.
* * * * *